In this paper we investigate the possible benefits and drawbacks of using a previously proposed ldquosoftrdquo ranging algorithm for tracking moving objects in indoor scenarios. The objects considered in this work could be either passive point scatterers or active relays. A number of ultra-wide band transceivers are deployed throughout the environment, and they are used to estimate multi-path prop...
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As battery capacities are a key limiting factor of wireless sensor networks, harvesting energy from the environment is very attractive. For outdoor applications, solar power seems to be the best suited energy source. However, the amount of energy delivered from the sun changes significantly over the year, which makes the dimensioning of the panel difficult. In this paper we discuss the most import...
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In this paper, we jointly optimize the training interval length and the power allocation for MIMO (multiple-input multiple-output) flat fading channels when a maximum a posteriori (MAP) detector is used at the receiver and the training and data powers are allowed to vary. We calculate the equivalent signal-to-noise ratio (SNR) at the output of the MAP detector. Based on this expression, we define ...
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In this paper, the impact of the polarization on the performance of the multiple-input multiple-output (MIMO) channel with cross-polarized antennas has been investigated based on the outdoor macrocell measurement at 2.53 GHz. A simple model which can capture the major characteristics of the cross polarized channel is proposed. The effective polarization rotation during the propagation is evaluated...
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We study the design of linear precoders for maximization of the mutual information in MIMO systems with arbitrary constellations and with perfect channel state information at the transmitter. We derive the structure of the optimum precoder and we show that the mutual information is concave in a quadratic function of the precoder coefficients. An iterative algorithm is also proposed to find this op...
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In this paper issues in the implementation of a recursive least squares (RLS) multiple-input multiple-output (MIMO) decision-directed channel estimation (DDCE) and tracking algorithm for spatial multiplexing are discussed. Problems addressed are a simple calculation of the inverse autocorrelation matrix and schemes of training data or pilot symbols. While there is much work spend in evaluating pil...
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At the onset of the ubiquitous computing era, systems need to respond to a variety of challenges, in order to capitalize on the benefits of pervasiveness. One of the pivotal enablers of pervasive computing is the RFID technology which can be successfully applied in numerous applications. However, the interaction of such applications with sensitive personal data renders the need for assuring confid...
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An RFID system using many RF tags has some advantages over a bar code system such as simultaneous multi-reading and long read range. Especially, it has been strongly desired by logistics and the retail industry for efficiency of operation. Recently, user-friendly RFID systems are being studied. We focused on a gate system using RFID technologies. It will be very useful for the efficiency of invent...
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In this article we discuss the realization of antenna gate structures for inductively coupled passive HF RFID systems. Antenna gates are currently used in several applications, from industrial tracking to access control: in these structures the identification process is realized with the use of more antennas disposed in a configuration that makes them similar to doors. Nowadays these structures ca...
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We present an accurate SER estimation method for low duty, QPSK modulated, Direct Sequence Impulse Radio (DS-IR) over a frequency selective channel with RAKE reception. The approach is a useful novelty since the existing SER estimation methods for DS-IR are problematic in the low duty case because they are accurate only when the number of pulses per symbol is high. The approach is exploited to stu...
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We allocate power to maximise ldquosocial benefitrdquo in the uplink of a CDMA cell populated by data terminals, each with its own data rate, channel gain, willingness to pay (wtp), and link-layer configuration, and with energy supplies that are limited for some, and inexhaustible for others. For both types, appropriate performance indices are specified. The social optimum can be achieved distribu...
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In this paper, a novel optimum data-aided timing offset estimator that only relies on symbol-rate samples for frame-level timing acquisition is derived based on the maximum likelihood criterion. For this purpose, we exploit the statistical properties of the power delay profile of the received signals to design a set of the templates to ensure the effective multipath energy capture at any time. We ...
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Relay based multihop cellular system is a promising technique to improve the signal quality in wireless networks. Here, we propose the channel partitioning and relay positioning schemes so as to maximize the number of users admitted in a cell. A user is admitted if the required rate can be provided to it. Based on this scheme, signal to interference and noise ratio (SINR) received by base station ...
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